Compass.



C. L. BERGER.

COMPASS.

APPLICATION FILED I'EB.29, 1912.

1,1 1 5 ,774. Patented Nov. 3, 1914 THE NORRIS PETERS CDI. PHON-LITHO.WASHINGTON. D. CA

UNITED sTArEs rarnur onirica.

CHRISTIAN L. BERGER, OF BOSTON, MASSACHUSETTS.

ooivrrass;

b all lw hom t may concern i Be it known that L'Ciins'rniiv L. BERGER, acitizen of the United States, and resident of Boston, in the county ofSuolk and State of Massachusetts, have invented an Improvement inCompasses, of which the following description, in connection with theaccompanying drawings, is a specification, like letters on the drawingsrepresenting like parts.

This invention relates to a compass such as is ordinarily employed insurveyors7 transits and like instruments. The compass in such aninstrument comprises a magnetic needle mounted in a shallow circularinclesure having a `glass top, and having means to lift the needle olfits pivot to hold it in any Xed position and to prevent wearing down thepivot when the instrument is not in use. Within such inclosure andunderneath the glass is also usually arranged a plate having markedthereon the indications for degrees, and such plate is usually looselycontained within the inclosure so that it may be shifted orset to adjustthe compass for magnetic variation either to east or west of true northas required for the particular locality where the instrument is beingused This plate is termed the variation ring, and is preferably madewith a short portion or segment having teeth cut therein which arearranged to mesh with a pinion on the outside of the inclosure in aconvenient position to be operated to adjust the variation ring. Themeans or the lifter to raise the needle off its pivot projects throughan opening in the inclosure, at a different point from the openingprovided for the variation ring setting device, and the outer end of thelifter is engaged by a cam or screw to be depressed thereby and thus toraise the inner end, and lift the needle ofi3 its pivot. This formerconstruction has been found to be very objectionable and defective inthat two openings into the inclosure were necessitated, through whichopenings dust easily penetrated to such an extent that the openings werefrequently clogged, thus impairing the operation of the lifter and theadjustment of the variation ring, as well as affecting the sensitivenessof the instrument and chilling the pivot and also clouding the glass. Astill further objection to such a construction wherein openings wereformed Speccation of Letters Patent.

Application filed February 29, 1912.

Patented Nov. e, 1914.y

Serial No. 630,753. l

into the needle inclosure is that moisture, ram, or snow would easilydrift in and consequently might rust the pivot of the needle i aswell asthe needle itself, and vthus seriously aLect the accuracy of thecompass.

It is an object ofthis invention toimprove and perfect such compasses bypre` venting the entrance of dust or moisture `into ythe inclosure wherethe needle is mounted, and thus to eliminate all danger of iinpairingthe sensitiveness and ,accuracyy ofl the needle through such clogging orrust of the needle or its pivot.

lt is also an object of the invention to provide means to adjust thevariation ring and to operate the needle-lifter at the same point, andalso to protect both the opening for the needle-lifting means and theopening for the variation setting meansby a single preferred embodimentof the invention is` illustrated, Figure l shows in plan view asurveyors compass such as is usually provided in a transit, the drawingshowing a portion of the covering glass broken away; Fig. 2 is a view,partly in cross-section, on the line 2-2`of Fig. l; Fig. 3 is anenlarged detail view partly in section of the protecting device affixedto the compass outsider of the needle inclosure and containing both themeans to operate the needle-lifter and to adjust the variation ring; andFigs. 4

vand 5 show views in elevation and partly in section of modified formsof the means to operate the needle lifter `and to adjust thevariation-ring.

l is the base of a compass box formed in the usual manner, with anupstanding tiange 2 and an annular margin 3. Fitting closely to thefiange 2 and resting on the margin 3 is a circulary ring ilhaving ashelf :i on which the glass 6 rests. Preferably'the inner top portion ofthe ring 4 is threaded, and a covering retaining ring 7 is arranged toscrew' into said threads to clamp the glass (S between the lower surfaceof the ring 7 and the flange 5. A steel pivot 8 is afiXed to a plug 9threaded through the central aperture in the base 1 in the usual manner,and mounted to swing on this pivot is the needle 10, Resting looselyonthe flange 2 is a variation ring 11 on which may be marked the degreesof the circle in usual manner. A segment of this ring 1 is formed withteeth, as indicated at 12, and the ring 11 is capable of being slid onthe flange 2 by suitable manipulation of a gear outside the inclosuremeshing with the toothed segment 12, as will be described. Tn orde-r tolift the needle 10 off its pivot, a li ter 13 of usual form is provided,which lifter projects through a suitable aperture 1i in the flange 2extending outside the ins closure and over the marginal portion 3 of thecompass base. Preferably, and as herein shown, the lifter 13 extendsthrough the flange 2 underneath a portion of the toothed segment 12 inthe variation ring, and preferably also the gear to operate saidvariation ring extends through an aperture in the flange 2 directly overthat through which the lifter 13 projects. This construction enables themeans to operate the lifter and the means to adjust the variation ringto be arranged at the same point on the outside of the needle inclosure,and also enables a single protecting device to cover' both the aperturesthrough the flange 2 and ring 11.

VThe protecting device preferably comprises a cup-shaped member 15 whichmay be secured. to the marginal portion 3 of the base by suitablescrews, as shown in Fig. 1, said member fitting closelyagainst theoutside of the upstanding ring 1i, a portion of said member being cutaway as indicated at 16 in Fig. 1, to more closely lit the ring l and tocover the entire width of the opening through which the gear to operatethe variation ring must pass, as will be readily seen on reference toFig. 1. Preferably also the member 15 is arranged to contain the meanstov operate both the lifter and the variation ring, said member havingits lower portion threaded, in which a plate 17 is adapted to bescrewed, said plate having a hub 1S threaded to receive the stem 19 of athiunb screw 20, which stem engages the j projecting outer end of thelifter 13, as

clearly shown in Fig. 3. Manipulation of the` thumb screw 20 acts tooscillate the lifter 13 and to 'aise and lower the needle 10.Surrounding the hub 18 and resting Y upon the plate 17 is positioned thegear 21,

which gear is in mesh with the toothed segment 12 of the variation ring.This gear Q1 is formed with an upstanding hub Z2 projecting above themember 15 and having a plurality of spanner holes 23 so that the gearmay be easily rotated to adjust the j variation ring 1.1. Preferably aspring 2li is interposed between the top of the gear 21 and-the roof ofthe member 15.

In operating the devices just described, the needle may be independentlyraised from its pivot, and the variation ring may be independentlyadjusted to any desired position from the same point or side of thecompass, as shown, This construction is of considerable advantage,saving the operations formerly required of making such adjustment fromdifferent and usually opposite points of the compass, which necessitatedtheoperator either moving around the compass or reaching vacross itsface. The protecting member 15 covering both apertures in the needleinclosure through which the adjusting mechanism must work absolutelyprevents the entrance of dust and the consequent clogging of .themechanism, and also prevents the entrance of moisture, rain, or snow,and consequently eliminates the danger of rust spoiling the pivot or theneedle 1() and impair-ing the efliciency and sensitiveness of thecompass thereby. It will be noted that in the preferred constructionherein illustrated, the thumb screw 2O is mounted concentrically withthe gear 21 and with the hub 18, although such an arrangement is notnecessary and the invention is to be understood as not limited to thisform. A further feature in the preferred form herein shown is that thetop 20 of the thumb nut overhangs and protects the upstanding portionsof the hubs 2:2 and 18, thus serving as a further means of preventingmoisture from penetrating` into the interior of the member `15 or of theneedle inclosure.

The advantages incident to this construction will be readily apparent,as the sensitiveness and accuracy of such a. compass is largelydependent upon the balanced relation of the` pivot and needle, and theentrance of dust in the needle inclosure as well as the formation ofrust upon either needle or pivot is detrimental to the accuracy of theinstrument. It is of the greatest importance in an instrument of thiskind to prevent the accumulation of rust, either on the pivot or on theneedle itself. Rust may easily be occasioned through vapor or the slightmoisture in the air, which naturally permeates through the slightestopenings in the compass inclosure, such danger being especially presentduring rainy or foggy weather or, for example, when an instrument istaken into a mine for underground work, where water often drips downdirectly upon it. My invention elfectually eliminates all such danger.

TheA modiiications shown in Fig. l are quite similar to the preferredform illustrat-ed in Fig.v 3, but of a simpler construction, wherein theplate 17 is discarded, the thumb nut 2O being threaded directly throughthe center of the gear Q2, which gear has its hub in threaded engagementWith a nut 25 locked thereto by a set screw 26 and arranged to overhangand bear upon the top of the protecting device 15. The modificationsshoWn in Fig. 5 comprise a sleeve 26 formed integrally with theprotecting member l5, which member' is fitted with a re* movable top 15asuitably flanged to fit on to the edge of the member l5, as shown, tofacilitate the assembling of the parts. The gear 22 in this form is heldyieldingly up by a flat spring 27 against a nut 28 threaded onto the topportion of the sleeve 26. The operation of the variation-ring settinggear and of theneedle-lifting device in these modifications issubstantially identical with that of my preferred form shown in Fig. 3and need not be further described.

Having described my invention, What I claim as new and desire to secureby Letters Patent is:

l. A surveyors compass, having amagnetic needle, a lever to render saidneedle operative or inoperative, anda variation ring, asubstantiallydustproof inclosure therefor, containing said needle and ring, means toadjust said variation ring, extending through said inclosure, andseparate means, held by said ring adjusting means, to actuatesaid lever.to render the needle operative or inoperative.

2. A surveyors compass, having a magnetic needle, a lever to render saidneedle operative or inoperative, and a variation ring, a substantiallydustproof inclosure therefor, containing said needle and ring, meansextending into said inclosure to adjust the variation ring, comprising ahollow sleeve and gear, and a device extending through said sleeve toactuate said lever to render the needle operative or inoperative.

3. A surveyors compass, having a magnetic needle and a variation ring, asubstantially dust-proof inclosure therefor, containing said needle andring, and having openings through the side Walls thereof, means passingthrough one opening to render the needle operative or inoperative, incombination With means passing through a second opening to actuate andadjust the variation ring, and a single protecting device constructedand arranged to cover both openings and prevent the entrance of dust andmoisture therethrough.

4. A surveyors compass, having a magnetic needle and a variation ring,vasubstantially dust-proof inclosure therefor, containing said. needle andring, and having openings through the side Walls thereof, means passingthrough one opening to render the needle operative or inoperative, meanspassing through a second opening to actuate and adjust the variationring, and a single protecting device constructed and arranged to coverboth openings and prevent the entrance of dust and moisturetherethrough, in combination With means passing through said protectingdevice to operate each of said means. v

In testimony whereof, I have signed my name to this specification, inthe presence of two subscribing witnesses.

CHRSTIAN L. BERGER.

W'itnesses DANIEL W. Wins, WILLIAM A. BERGER.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of latents, Washington, D. C."

